A conventional polarizing plate with high polarization efficiency is generally such that a cellulose-triacetate-based (hereinafter, referred to as is TAC) film, which serves as a protective film, is laminated on a polarizing film in which iodine or a dichroic dye is adsorbed and oriented in a polyvinyl-alcohol-based (hereinafter, referred to as PVA) film, with an aqueous solution of PVA resin, which serves as an adhesive, in a state of wet or semidry flowability.
However, since the water absorption and water vapor permeability of TAC is high, in a polarizing plate using TAC for the protective film, deterioration in polarization performance under a high humidity/high temperature environment, specifically, drop in polarization efficiency, hue shift, and light leakage under crossed nicols, has been significant.
In order to overcome these problems, polarizing plates that use a film made of a resin with low water absorption and low water vapor permeability for the protective film have been proposed.
For example, Japanese Unexamined Patent Publication No. 7-77608 discloses a polarizing plate such that a film serving as a protective film and made of a thermoplastic saturated norbornene-based resin is adhered to a PVA-based polarizing film using an acrylic-based adhesive or a polyester-isocyanate-based adhesive. After such a polarizing plate is subjected to an environment of 80° C. and 90% RH for 500 hours, the polarization efficiency is 95% or higher and the single transmissivity 38% or higher.
In addition, Japanese Unexamined Patent Publication 7-294732 discloses a polarizing plate such that a film having a photoelastic coefficient of 25.0×10−13 cm2/dyne or less, for example, a film made of an amorphous polyolefin such as Zeonex, or polymethyl methacrylate serves as a support for a polarizing element film, and the support is adhered to the polarizing element film using an acrylic-based adhesive. After such a polarizing plate is subjected to an environment of 60° C. and 90% RH for 100 hours, the pyschometric lightness is small.
However, although these polarizing plates are able to suppress a drop in polarization efficiency under a wet heat environment, it cannot be said that suppression of hue shift and light leakage is sufficiently realized.